JPH0515042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a method of manufacturing a thermal print head.

(Prior Art) FIG. 6 shows an example of a conventional pattern of a heat generating head in a thermal print head, in which common electrodes C and individual electrodes S are alternately arranged across a strip-shaped resistor R. be. According to this configuration, one heating dot is constituted by two mutually adjacent partitioned resistance portions M of the resistor which are partitioned by adjacent electrodes.

According to this configuration, it is necessary to arrange the segmented resistance parts M at twice the density of the heat generating heads, so it is impossible to make the segmented resistance parts M higher in density than the segmented resistance parts M.
Therefore, there is a limit to how high the density can be increased, and specifically, the heating dot density with such a configuration is limited to 12 dots per 1 mm.

(Problems to be Solved by the Invention) An object of the present invention is to increase the density of the arrangement of heating dots in a thermal print head.

(Means for Solving the Problems) The present invention provides a band-shaped heating resistor made of a thick film, with one side edge and the other side edge forming a pair with each other and partially facing each other in a staggered manner. By forming a plurality of electrodes so as to be located in the same shape, and then supplying power between the adjacent electrodes, the resistance of the resistor portion existing between the adjacent electrodes is increased, and the resistance of the resistor portion between the adjacent electrodes is increased. By supplying power between one of the pair of electrodes and the electrode adjacent to the other pair of electrodes, the resistance of the resistor part existing between them is increased. shall be.

It is generally known that when excessive power is supplied to a thick-film resistor for a short period of time, the resistance value increases. This is because the contact area between the resistive particles that form the resistive paste is overheated and fused by the supplied electricity, and the resistance value increases as the contact between the particles is broken. It will be done.

For example, if the power supplied for printing in a heating resistor array of a thermal print head is, for example, 60 W/mm ² , then approximately twice that power, 120 W/mm ² , for example, 120 mj/mm ² is applied.
If it is supplied for 1ms, the resistance value will rise rapidly. Note that if an extremely large amount of power is supplied, the resistor portion between the electrodes will melt and its resistance value will become extremely large.

Due to this increase in resistance value, the resistor portions formed between adjacent electrodes and between opposing electrodes become substantially open or isolated. Therefore, if the distance between the electrodes is made sufficiently narrow, it is possible to form the resistor with almost no gap between adjacent resistor parts. Therefore, it is possible to fabricate a high-density array of heating dots without making the resistor pattern too fine.

(Example) An example of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a substrate made of an insulating material such as ceramic, and 2 a heat generating resistor formed as a thick film on the surface of the substrate 1, which is formed into a long strip-like shape. Reference numeral 3 indicates a plurality of first electrodes formed to overlap one side edge of the resistor 2, and reference numeral 4 indicates a plurality of second electrodes formed to overlap the other side edge.

Actually, as shown in FIG. 1, the electrodes 3 and 4 are first formed, and then, as shown in FIG. 2, the resistor 2 is formed so as to cover the tips of the electrodes 3 and 4. The first and second electrodes 3 and 4 face each other as a pair, and the paired electrodes are positioned in a staggered manner so as to partially face each other.

Next, a resistor 2 is formed of a thick film so as to include the tips of each electrode 3 and 4 and span between both electrodes.
A process is performed to substantially open or isolate the resistor portions 2A located between the pair of electrodes 3 and 4, that is, the resistor portions constituting the heating dots, from each other.

Therefore, the power between adjacent electrodes is 2 to 3 higher than that applied between the electrodes in normal use.
It supplies about 100% of power. Due to this power supply, the resistance values of the resistor portions 2B (shaded portions in FIG. 2) between the adjacent electrodes 3 and between the adjacent electrodes 4 are, for example, two to three times higher than other portions. Become. In this way, by increasing the resistance of the resistor portion 2B, the adjacent electrodes are substantially open or isolated.

Next, for example, if the electrode 3A and the electrode 4A are paired together to form one resistor portion 2A (see Figure 3), then the electrode 4B adjacent to the electrode 4A and the electrode 3A During this time, two to three times more power is applied than normally applied between the opposing electrodes.

Due to this power supply, the resistance value of the resistor portion 2C (shaded portion in FIG. 3) between the electrodes 3A and 4B becomes two to three times higher than that of other portions, especially the resistor portion 2A. In this way, by increasing the resistance of the resistor portion 2C, both sides of the resistor portion 2A are substantially open or isolated.

Note that the resistor part 2C is connected to the resistor part 2C before the resistor part 2B.
Of course, the resistance may be increased.

Each resistor portion 2A forming a heat generating dot in this way has a high resistance resistor portion 2B, 2
C and become electrically independent. FIG. 4 shows this state. As will be understood from now on, it becomes possible to make the density of the heating dots the same as that of the electrode pattern.
Specifically, it has been confirmed that the density of resistor portions constructed by this method can be up to 16 per mm.

FIG. 5 shows another embodiment of the present invention, in which the tip of each electrode is not straight but triangular instead. In this way,
The resistor portion 2A can be effectively widened.

Although not shown in the figure, it goes without saying that the surfaces of the resistors and electrodes are coated with glass or other material.

(Effects of the Invention) As detailed above, according to the present invention, the resistor portions constituting the heating dots are surrounded by a high resistance region, thereby making each resistor portion electrically independent. Therefore, it is possible to produce high-density heat-generating dots.

[Brief explanation of the drawing]

1 to 4 are plan views showing the manufacturing process of an embodiment of the present invention, FIG. 5 is a plan view showing an embodiment of the invention, and FIG. 6 is a plan view of a conventional example. 2...Resistor, 2A to 2C...Resistor part,
3, 4... Electrode.

Claims (1)

[Claims] 1. A plurality of electrodes are formed on one side edge and the other side edge of a band-shaped heat generating resistor made of a thick film so as to be arranged in pairs and partially facing each other in a staggered manner, Then, by supplying power between the adjacent electrodes, the resistor portion existing between the adjacent electrodes is made to have a high resistance, electrically separating the adjacent electrodes, and forming a pair. By supplying power between one of the electrodes and another electrode adjacent to the other paired electrode, the resistance of the resistor portion existing between them is increased, thereby increasing the resistance of each pair. A method for manufacturing a thermal print head, in which a resistor portion serving as a heating dot between electrodes is surrounded by a high-resistance region.